Sulfur is a common mineral in nature and has very important medicinal value. However, in the eyes of rubber people, sulfur may have more important use than medicine - the vulcanizing agent in rubber products. The origin of sulfur and rubber is also told by Mr. Charles Goodyear, the father of rubber.
The historical origin of rubber and sulfur
As an ancient material, rubber has long been used by ancestors. At that time, rubber was mostly used for adhesives and waterproof garments. Because rubber has a fatal flaw, it is too sensitive to temperature. When the temperature is slightly higher, it will become soft and sticky, and it will smell bad; when the temperature is low, it will become brittle and hard.
In the summer of 1834, Goodyear visited New York's Indian Rubber Company. He learned that this property of rubber plagued the entire rubber industry, but rubber has a series of excellent properties such as high elasticity, plasticity, durability, waterproofness and insulation. Specific determination to study the modification of rubber. In January 1839, Goodyear accidentally put rubber, lead oxide and sulfur together and heated it to give a leather-like substance. This material does not decompose at higher temperatures than the commonly known elastic rubber. After a series of improvements, Goodyear was finally convinced that the material he prepared would not decompose at any temperature below the boiling point. "Rubber vulcanization technology" came out. Therefore, it is precisely because of the unintentional discovery of Goodyear that the performance of rubber is improved, in order to commemorate Charles 38 years after Goodyear's death. Goodyear's great contribution to the US rubber industry, Frank. Keblin named the tire rubber company he founded, Goodyear, which is now one of the top three tire manufacturers in the world.
Classification of sulfur
The sulfur used in the rubber industry is sulfur yellow powder, insoluble sulfur, colloidal sulfur, precipitated sulfur, sublimed sulfur, desulfurized sulfur and non-crystalline sulfur. The first three are more commonly used.
Sulfur powder: It is the most widely used sulfur in the rubber industry.
Insoluble sulfur: a homopolymer of sulfur, also known as polymeric sulfur. Its biggest advantage is that the product is not easy to be sprayed, and it is widely used in rubber products such as high-grade steel radial tires.
Colloidal sulfur: A paste made by grinding sulfur powder or settled sulfur together with a dispersing agent. Mainly used in latex products.
The role of sulfur in rubber products
The traditional rubber has excellent performance, and it is necessary to form a three-dimensional network space structure from the linear macromolecular chain through cross-linking. The cross-linking process is also commonly referred to as vulcanization of rubber because the initial cross-linking is achieved with sulfur. After the rubber is vulcanized, the properties change as the structure changes: the rubber no longer flows, it is no longer soluble in its good solvent, the modulus and hardness are improved, the mechanical properties are improved, the aging resistance and chemical stability are improved. . Therefore, only after the discovery of sulfur, rubber has become a polymer material with excellent performance and wide application.
Of course, the formation of a vulcanization network in the rubber needs to be combined with other compounding agents such as an active agent and a promoter to form a complete vulcanization system. With the development of the rubber industry, people have higher requirements for the performance of rubber products. The types and alternatives of sulfur are also being developed and produced.